$OpenBSD: patch-configure_in,v 1.3 2013/03/08 01:30:37 brad Exp $

adapt patch from http://enblend.hg.sourceforge.net/hgweb/enblend/enblend/diff/57db56afb9a9/configure.in

--- configure.in.orig	Sat Nov 24 14:57:20 2012
+++ configure.in	Sat Nov 24 15:01:33 2012
@@ -196,8 +196,26 @@ AC_CHECK_HEADER(boost/random/mersenne_twister.hpp, [],
                 AC_MSG_ERROR([Boost "mersenne_twister" header file is required to compile Enblend.]))
 AC_CHECK_HEADER(boost/scoped_ptr.hpp, [],
                 AC_MSG_ERROR([Boost "scoped_ptr" header file is required to compile Enblend.]))
+AC_CHECK_HEADER(boost/system/error_code.hpp, [],
+                AC_MSG_ERROR([Boost "error code" header file is required to compile Enblend.]))
 AC_CHECK_HEADER(boost/static_assert.hpp, [],
                 AC_MSG_ERROR([Boost "static_assert" header file is required to compile Enblend.]))
+
+
+LIBS="-lboost_system $LIBS"
+AC_MSG_CHECKING([for new Boost system library])
+AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include "boost/system/error_code.hpp"]],
+                                [[boost::system::generic_category();
+                                  boost::system::system_category()]])],
+               [AC_MSG_RESULT(yes)],
+               [AC_MSG_RESULT(no)
+                AC_MSG_CHECKING([for old Boost system library])
+                AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include "boost/system/error_code.hpp"]],
+                                [[boost::system::get_generic_category();
+                                  boost::system::get_system_category()]])],
+                               [AC_MSG_RESULT(yes)],
+                               [AC_MSG_RESULT(no)
+                                AC_MSG_ERROR([Boost "system" library is required to compile Enblend.])])])
 
 AC_ARG_WITH([boost-filesystem],
             [AS_HELP_STRING([--with-boost-filesystem],
